The invention relates to a circuit arrangement for operating recording nozzles in ink mosaic recording devices employing tubular drive elements which contain the recording fluid and which comprise electromechanical transducers, particularly piezo-electric tranducers, having a diameter which is variable in response to the application of different electrical voltage potentials applied thereto.
It is known, for example from U.S. Pat. No. 3,683,212, to record information on data carriers utilizing a pulsed device which serves to eject droplets of ink, and which employs a tubular ink receiving chamber which is surrounded by a piezo-electric transducer. The inner volume of such chamber is varied in response to an electric signal, particularly in such a manner that a contraction of the piezo-electric transducer takes place, applying compression forces to the quantity of ink contained within the chamber, resulting in the ejection of a droplet of ink from the associated recording nozzle. In such an arrangement, the ejection of the droplet of ink results from the short circuiting, by means of an electronic circuit arrangement, the applied voltage on the piezo-electric transducer, as a result of which the latter reacts, producing a sudden contraction of the transducer with the accompanying ejection of a droplet of ink. Following such ink ejection, the electronic switching arrangement disconnects the short circuit with respect to the voltage applied to the transducer, so that the latter is again supplied with the original voltage and as a result returns to its expanded state.
A circuit arrangement for operating a piezo-electric transducer is also known from German OS No. 25 48 691 (U.K. Pat. No. 1,510,091) employing an electronic switch which is in a form of a transistor Darlington circuit, in conjunction with a transformer for effecting the operation of the associated piezo-electric transducer. In this arrangement, the ejection cycle for a droplet of ink is initiated by an appropriate operation of the circuit arrangement to first effect an expansion of the drive elements, from their initial rest state, by the connection of an appropriate voltage potential to the piezo-electric transducer. The drive elements are then brought from the expanded state into a contracted state, over the circuit arrangement, by effecting a change in polarization of the control voltage, resulting in ejection of the ink droplets.
When utilizing known arrangements of this type, it is necessary to employ the entire circuit arrangement for each individual-electric transducer to be operated. The two voltage potentials for the piezo-electric transducer are, in this case, connected by the same electronic switching element. The change in potential which must take place for the contraction of the piezo-electric transducer should be particularly noted. As may be ascertained from the known prior art, this change in potential must take place considerably more rapidly than the change in potential which serves to expand the piezo-electric transducer involved. Further, where a large number of piezo-electric transducers are employed, the high voltages and currents which occur are likely to affect the adjacent connection lines.